In recent years, disorders like diabetes, hypertension, dyslipidemia and obesity which can be a risk factor for arteriosclerotic disorders have been rapidly increasing due to changes in life style with improvements in living standard, i.e., high calorie and high cholesterol type diet, obesity, lack of exercise, aging, and the like. It is known that, although being a risk factor independent of each other, overlap of the disorders can cause an occurrence of arteriosclerotic disorders at higher frequency or aggravation of the disorders. As such, with the understanding of a condition having a plurality of risk factors for arteriosclerotic disorders as metabolic syndrome, efforts have been made to elucidate the cause of the syndrome and to develop a therapeutic method therefor.
Angiotensin II (herein below, it may be also abbreviated as AII) is a peptide that is found to be an intrinsic pressor substance produced by renin-angiotensin system (i.e., RA system). It is believed that pharmacological inhibition of angiotensin II activity can lead to treatment or prevention of circulatory disorders like hypertension. Accordingly, an inhibitor for angiotensin converting enzyme (ACE) which inhibits the enzyme promoting the conversion of angiotensin I (AI) to angiotensin II (AII) has been clinically used as an inhibitory agent for RA system. Furthermore, an orally administrable AII receptor blocker (Angiotensin Receptor Blocker: ARB) has been developed, and losartan, candesartan, telmisartan, valsartan, olmesartan, and irbesartan are already clinically used as a hypotensive agent. It is reported by many clinical or basic studies that, as having not only a hypotensive activity but also other various activities including an anti-inflammatory activity, an endothelial function improving activity, a cardiovascular remodeling inhibiting activity, an oxidation stress inhibiting activity, a proliferation factor inhibiting activity, and insulin resistance improving activity, ARB is useful for cardiovascular disorders, renal diseases, and arteriosclerosis, etc. (Non-Patent Document 1 and 2). Most recently, it is also reported that ARB particularly has a kidney protecting activity which does not depend on a hypotensive activity (Non-Patent Document 3).
Meanwhile, three isoforms, i.e., α, γ, and δ, are identified so far as peroxisome proliferaor-activated receptors (PPARs) which belong to a nuclear receptor superfamily. Among them, PPARγ is an isoform that is most abundantly expressed in an adipose tissue and it plays an important role in differentiation of adipocytes or metabolism of glycolipids. Currently, thiazolidinedione derivatives (i.e., TZD) like pioglitazone or rosiglitazone are clinically used as a therapeutic agent for diabetes having PPARγ activation activity, and they are known to have an activity of improving insulin resistance, glucose tolerance, and lipid metabolism, etc. Further, it is recently reported that, based on activation of PPARγ, TZD exhibits various activities including a hypotensive activity, an anti-inflammatory activity, an endothelial function improving activity, a proliferation factor inhibiting activity, and an activity of interfering RA system, etc. It is also reported that, according to such multiple activities, TZD shows a kidney protecting activity particularly in diabetic nephropathy without depending on blood sugar control (Non-Patent Document 4, 5, 6, 7, and 8). Meanwhile, there is also a concern regarding adverse effects of TZD caused by PPARγ activation like body fluid accumulation, body weight gain, peripheral edema, and pulmonary edema (Non-Patent Document 9 and 10).
It has been recently reported that telmisartan has a PPARγ activation activity (Non-Patent Document 11). It has been also reported that the irbesartan has the same activity (Non-Patent Document 12). These compounds have both a RA system inhibiting activity and a PPARγ activation activity, and thus are expected to be used as an integrated agent for prevention and/or treatment of circulatory disorders (e.g., hypertension, heart disease, angina pectoris, cerebrovascular disorders, cerebral circulatory disorders, ischemic peripheral circulatory disorders, and renal diseases, etc.) or diabetes-related disorders (e.g., type 2 diabetes, diabetic complications, insulin resistant syndrome, metabolic syndrome, and hyperinsulinemia, etc.) without increasing a risk of body fluid accumulation, body weight gain, peripheral edema, pulmonary edema, or congestive heart failure that are concerned over the use of TZD (Patent Document 1). Among them, for diabetic nephropathy, a synergistic prophylactic and/or therapeutic effect is expected from multiple kidney protecting activity based on activities of RA system inhibition and PPARγ activation.
As a compound having the activities above, the pyrimidine and triazine derivatives (Patent Document 1), imidazopyridine derivatives (Patent Document 2), indole derivatives (Patent Document 3), and imidazole derivatives (Patent Document 4) have been reported. Of these, a group of compounds that are characterized by having an oxadiazolidinone ring or a thiadiazolidinone ring on biphenyl ring is described in Patent Document 1, and a compound having the pyrimidinone skeleton like the following formula (A) is disclosed (see, Example 219 of Patent Document 1):

However, according to the group of compounds described in Patent Document 1, no tetrazolyl group is present on the biphenyl ring.
The compounds represented by the following formula (B) which have angiotensin II antagonistic activity and are useful for treatment of hypertension, heart failure, intraocular hypertension, etc. have been reported (Patent Document 5):

[in the formula, R represents C1-4 alkyl, R1 represents a hydrogen, C1-4 alkyl, aryl, or aryl alkyl (herein, aryl represents phenyl, naphthyl, 2-thienyl, or 2-furanyl) and the like, R2 represents C1-4 alkyl and the like, R3 represents a hydrogen and the like, X represents CO and the like, and Z represents carboxyl or tetrazolyl and the like]. However, in the document, a compound in which a heteroaryl group like thienyl group or furanyl group is directly bonded to R1 is not specifically described. Further, with respect to pharmacological activity, there is no description or suggestion regarding the PPARγ activation activity or treatment of diabetes, obesity, or a metabolic syndrome.
The compounds represented by, the following formula (C) which have angiotensin II antagonistic activity and are useful for treatment of hypertension and heart failure have been reported (Patent Document 6):

[in the formula, R1 represents a C1-6 alkyl group and the like, R2 represents a hydrogen atom, a halogen atom, a C1-6 alkyl group and the like, R′3 represents —(CH2)n-heterocyclic group (herein, n represents an integer of from 0 to 5) and the like, and R4 represents the above formula C′ and the like]. However, even in this document, a compound in which a heteroaryl group is directly bonded to R′3 is not specifically described. Further, with respect to pharmacological activity, there is no description or suggestion regarding the PPARγ activation or treatment of diabetes, obesity, or a metabolic syndrome.